1. Field of the Invention
The present invention relates to a data transmission/reception method in Near Field Communications (NFC). More particularly, the present invention relates to a communication method for enhancing data throughput between an initiator and a target that perform NFC.
2. Description of the Related Art
Near Field Communications (NFC) is a method for communication between devices that are spaced from each other within about a 10 cm distance. In NFC protocol stacks, the NFCIP-1 standard is used on physical layers of ISO 14443. In NFCIP-1, devices used for the NFC (or NFCIP-1 devices) may operate either in Active mode or Passive mode. An NFCIP-1 device in a transmission mode is referred to as an initiator and an NFCIP-1 device in a reception mode is referred to as a target.
In Passive mode, an NFCIP-1 device does not have its own power source required for modulation of its own Radio Frequency (RF) field and thus cannot generate a request message by itself. Therefore, a communication must be started by an initiator at all times. In other words, once the initiator (in Active mode) sends a request message through the RF field, the target (in Passive mode) drives a receiver circuit with the power source provided through the RF field. If the initiator does not have any transmission data, the initiator will periodically transmit a symmetry (SYMM) frame.
In response to the SYMM frame or an Information (I) frame received from the initiator, the target responds to the initiator by sending back the received frame to the initiator, with the frame sent back having its own data additionally inserted therein. Thus, the throughput, i.e., data transfer rate, of data transmitted from the target depends on the frequency of the I frame or the SYMM frame received from the initiator.
Moreover, with regard to NFC in the current Logical Link Control Protocol (LLCP) version, the initiator has to wait for reception of a response frame after transmitting a request frame. This waiting is referred to as response waiting time. Due to such a wait, data transfer may be delayed by the amount of response waiting time (RWT). Furthermore, there are several additional overheads to every request frame transmitted by the initiator. As a result, as the amount of data to be transmitted between NFC devices increases, i.e., as the number of request frames transmitted by the initiator increases, the number of RWTs for each request frame increases, and the same overhead is separately transmitted through a plurality of request frames. The aforementioned results in an increase in the amount of data and in turn causes a degradation in the data transfer rate between the NFC devices.
To solve those problems, there is a need for a fundamental method for improving a data transfer rate between NFC devices.